Put four plates into the fridge to chill. Wrap the beef tightly in baking parchment and freeze for 1 hr until firm but not frozen solid. Slice the beef into 12 rounds using a very sharp knife.

Put the beef slices between two sheets of baking parchment and flatten until paper thin using a rolling pin or the flat side of a meat mallet. Arrange 3 slices of beef over each of the chilled plates.

Toss the rocket or watercress with 1 tbsp of the olive oil and a little seasoning, then pile into the centre of each plate. Drizzle the remaining olive oil over the beef and scatter over the shaved parmesan. Season with sea salt and plenty of black pepper, then serve immediately with the lemon wedges for squeezing over.